Dissimilar Electron Beam Welds of Nickel Base Alloy A625 with a 9% Cr-Steel for High Temperature Applications

Welding of thick walled components with an electron beam has great potential due to the minimal heat input, high reproducibility and cost-efficiency. In the present work electron beam welding was used to weld 50mm thick plates of cast Ni-base alloy A625 to ferritic/martensitic 9% Cr steel plates. The welds were creep exposed at 625°C with stress levels ranging between 156 - 100MPa. Microstructure analysis of the weld-seam and the heat affected zone was carried out using metallography and scanning electron microscopy employing the EBSD technique to determine the location of the creep rupture. Creep fracture is located in the heat affected zone of the 9% Cr steel. Electron beam welded samples were compared to shield metal arc welded samples regarding
welding and creep resistance. The performance and related microstructure properties of the electron beam welded specimen are more than competitive to conventional metal-arc-welding procedures.